Evaluation of the Quasi‐Biennial Oscillation in Global Climate Models for the SPARC QBO‐Initiative
The Quasi-biennial Oscillation (QBO) is the dominant mode of variability in the tropical stratosphere, however many general circulation models (GCMs) still have a difficult time reproducing this oscillation. The QBO was evaluated in thirteen models that participated in the SPARC QBO-Initiative. Via experiments with observed and annually repeating sea surface temperatures, the response of the QBO to interannual variability in sea surface temperatures (SSTs) was examined.
QBO impacts the variability of the stratosphere and troposphere and is a source of seasonal predictability. Representing this stratospheric oscillation in GCMs accurately could positively affect the representation of tropospheric variability as well as improve seasonal prediction.
We find that the models that participated in QBOi well represent the QBO period and amplitude at 10 hPa, however other metrics, such as latitudinal extent, the amplitude at and below 50 hPa, representation of easterly and westerly phases need improvement. Characteristics of the QBO are very similar whether or not the prescribed SSTs vary interannually. Mean QBO periods and variability are more sensitive to SSTs in models with parameterized gravity wave sources.